Point contact mounting for ignition distributors

ABSTRACT

Pitting of the ignition contacts of an ignition distributor is avoided by effecting relative displacement or wiping action between the fixed and movable contacts. The wiping action is achieved by shifting the breaker arm axially on its pivot shaft in response to variations in the intake manifold pressure of the associated internal combustion engine. The contacts may therefore be associated with a distributor which does not employ manifold or vacuum advance characteristics. When the breaker arm pivot shaft is parallel to the distributor rotor shaft, provision of helically extending lobes on the distributor cam will also effect advance-retard characteristics in response to axial movement of the breaker arm on its pivot shaft. Alternatively, with a distributor cam having lobes extending parallel to the axis of the rotor shaft, inclination of the pivot shaft for the breaker arm likewise effects the advance-retard characteristics. In all arrangements, axial shifting of the breaker arm on its pivot shaft effects a wiping action between the fixed and movable contacts.

I United States Patent 11 [72] Inventor Roger Jenn Hubert 2,688,054 8/1954 Berlyn et al 200/31 Paris, France 2,854,534 9/1958 Beauclair 200/27 X No. 239168 9 3,009,027 I l/l96l Pelagatti 200/31 i e eb. l 70 451 Patented Sept. 14,1911 "?f" [73] Assignee Ducenkr a Ck Attorney-lmir|e and Smiley Paris, France 3; Pnomy ABSTRACT: Fitting of the ignition contacts of an ignition dis- 2:32 tributor is avoided by effecting relative displacement or wiping action between the fixed and movable contactsv The wiping action is achieved by shifting the breaker arm axially on its [54] POINT CONTACT MOUNTING FOR IGNITION pivot shaft in response to variations in the intake manifold DISTRIBUTORS pressure of the associated internal combustion engine. The 9 Chin, 6 Drawing gm contacts may therefore be associated with a distributor which does not employ manifold or vacuum advance characteristics. [$2] [1.5. CI 200/19 R, when the breaker arm pivot shaft is parallel to the distributor ZOO/22, 200/25, 2(30/31 rotor shaft, provision of helically extending lobes on the dis- [Sl Int. Cl "0"] 19/00 rrib tor cam ill also efiect advarme-retard characteristics in [50] Field Of Search ZOO/22, 25, s nse to axial movement of the breaker arm on its pivot 27, 19 R shaft. Alternatively, with a distributor cam having lobes extending arallel to the axis of the rotor shaft, inclination of the [56] References Cited pivot shzft for the breaker arm likewise effects the advance- UNITED STATES PATENTS retard characteristics. In all arrangements, axial shifting of the 2,096,158 10/1937 Bryant... 200/22 breaker arm on its pivot shaft effects a wiping action between 2,096,294 10/ I937 Bryant 200/31 the fixed and movable contacts.

lia

IV/A

PATENTEDSEPMISYI 3504354 sum 1 or 2 FIG] INVENTOR ROGER HABERT BY 341 1 Si nmaucvs PATENIEUSEPWQH 3,604 864 saw 2 [If 2 INVENTOR ROGER HABERT BY 9m #5114? ATTORNEYS POINT CONTACT MOUNTING FOR IGNITION DISTRIBUTORS BACKGROU ND OF THE INVENTION In the usual induction coil system used for firing the spark plugs of an internal combustion engine, a fixed ignition point contact is associated with a breaker arm carrying a further contact and the breaker arm is pivoted on a shaft so that make and break of the contacts is established by engagement between the rubbing block on the breaker arm and the dis tributor cam. It is well known that in such systems, the contact points pit or corrode rather rapidly so that frequent replacement of the contact points is required. This problem persists despite the despite the fact that ignition points contemporarily are made of relatively exotic materials which resist the pitting or corroding to a greater extent than materials which have been previously used. To minimize this pitting or corroding, it has previously been suggested to incorporate a separate mounting for the breaker arm which is controlled by the usual vacuum advance diaphragm associated commonly with ignition distributors so that as the breaker arm is moved with respect to the distributor cam to effect the requisite advanceretard characteristics, it also causes movement of its contact point with respect to the fixed contact point so point so that a wiping or rubbing action is attained between the fixed and movable points. Such prior arrangements have, however, been restricted to use in conjunction with vacuum advance distributors.

BRIEF SUMMARY OF THE INVENTION The present invention is directed to an arrangement so as to obtain a wiping action between the fixed and movable contacts of ignition point contact arrangement which is not restricted to use in conjunction with a vacuum advance distributor and therefore may be used with any desired type of distributor.

In essence, the present invention involves the utilization of a breaker arm mounted on a pivot shaft therefor and which is axially shiftable on such pivot shaft so as to effect relative wiping action between the fixed and movable contacts of the ignition point system. The axial shifting of the breaker arm is effected by a desired mechanism which will periodically effect such shifting and, conveniently, the actuating mechanism may take the form of an actuator such as a bellows or diaphragm controlled by the negative pressure in the intake manifold of an internal combustion engine and suitably linked to mechanism for effecting the axial shifting or the breaker arm as aforesaid.

In addition to the above, by shifting the breaker arm in a path parallel to the rotor shaft of the distributor and providing helically extending cam lobes on the distributor cam, the aforementioned wiping effect between the fixed and movable contacts is effected simultaneously with advance-retard effects.

Alternatively, the pivot shaft for the breaker arm may be inclined with respect to the rotor shaft and the cam lobes conventionally formed, i.e., parallel to the axis of the rotor shaft whereby axial shifting of the contact breaker arm on the pivot shaft which is inclined as aforesaid will effect requisite advance-retard characteristics.

BRIEF DESCRIPTION OF THE DRAWING FIGURES FIG. 1 is a plan view showing the breaker plate and cam of an ignition distributor and illustrating the ignition points and the mechanism for shifting the breaker arm according to the present invention;

FIG. 2 is a vertical section taken substantially along the plane of section 22 in FIG. I;

FIG. 3 is a view similar to Figure 2 but showing a modified form of the invention;

FIG. 4 is a view similar to FIGS. 3 and 2 but showing a still further modified form of the invention;

FIG. 5 is a partial view illustrating a form of the invention similar to that shown in FIGS. I and 2 but with modified form of distributor cam so that advance-retard characteristics are also obtained; and

FIG. 6 is a view similar to FIG. 5 but showing further modification for effecting advance-retard characteristics.

DETAILED DESCRIPTION OF THE INVENTION Referring now more particularly to FIG. I, reference character II] therein indicates the conventional breaker plate of an ignition distributor which mounts, in usual fashion, a fixed contact point 2 cooperable with a movable contact point 3 carried on the breaker arm 4 having an insulated boss portion pivotally received on the shaft 8 which, as is shown in FIG. 2, is suitably anchored to the breaker plate 1. In an entirely conventional manner, the breaker arm 4 is provided with a leaf spring 5 abutting the insulator piece 5' normally to urge the breaker arm 4 to pivot about the shaft 8 such that the contact 3 is urged toward the contact 2, it also being understood that as is conventional, the leaf spring 5 may also serve as a means for establishing electrical connection to the movable contact 3.

The breaker arm 4 carries a rubbing block 6 which is adapted to be selectively engaged by the lobes of the cam 7 to make and break the contacts 2,3 in entirely conventional fashion. In conventional vacuum advance distributors, the entire breaker plate is rotatable about the axis of the rotor shaft to which the cam 7 is affixed and a diaphragm actuator mounted on the housing of the distributor is provided with a suitable link or rod connected to the breaker plate for rotating the breaker plate with respect to the rotor shaft to effect the ignition advance-retard characteristics as is well known in the art.

In accord with the present invention as shown in FIGS. I and 2, the breaker plate 1 is fixed and the cam 7 may be actuated to impart the desired advance-retard characteristics by a conventional centrifugal mechanism. As shown in FIG. 2, the insulated hub of the breaker arm 4 is of an axial length substantially less than the pivot shaft 8 therefor and a suitable removable washer member 8' is fixed to the free end of the pivot shaft 8 and provided a seat for a compression spring 9 received in and seating within a recess in the corresponding end of the breaker arm boss. The opposite end of the breaker arm boss bears against an insulated bushing 10 having a reduced diameter portion 10a and diametrically opposed protrusions 10b. The breaker plate is provided with upstand ing tabs I3 and 14 mounting therebetween a pivot shaft 12 upon which a bellcrank I1 is pivotally received, one arm of the bellcrank ll being bifurcated as indicated by the reference characters Ila to straddle the reduced diameter portion [0a of the bushing I0 and upon which the protuberances or protrusions 10!; bear under the action of the compression spring 9. The other end III; of the bellcrank II is fixed to a stub shaft 11 which is provided with a transverse bore receiving and anchoring to the inner end of a link 15. A U-shaped sheet metal or like toothed cam member 17 is disposed as shown and the teeth thereon as is illustrated in FIG. I cooperate with a protrusion on a washer member I9 surrounding the shaft or link I5 so as to bear against the compression spring 16 and thereby vary the initial compression therein. The opposite end of the compression spring I6 bears upon a suitable actuator to which the link 15 is also secured. Such actuator may take the form ofa diaphragm similar to the diaphragm used for ordinary vacuum advance actuators for ignition distributors. In response to increasing negative pressure in the intake manifold of the internal combustion engine, the link I5 is moved in the direction of the arrow F in FIGS. I and 2 whereby to rock the bellcrank II about its pivot 12 and thus cause axial shifting of the breaker arm 4 along the shaft 8 in opposition to the compression spring 9. The compression spring 9 of course returns the breaker arm to the FIG. 2 position when the intake manifold pressure is at ambient atmospheric pressure.

With the above arrangement, it will be appreciated that normal fluctuations in the intake manifold pressure will cause the breaker arm to shift axially back and forth along the shaft 8 and thereby cause a relative wiping action between the movable contacts 3 and the fixed contact 2 whereby to minimize the normal pitting or corroding action which takes place between the breaker points of an ignition distributor mechanism.

With reference now to FIG. 3, wherein a modified form of the invention is shown, it will be seen that the bellcrank 11 in this case bears against an insulated button 10' seated within the open free end of the boss of the contact breaker arm which, in this case, extends beyond the pivot shaft 8 as shown. Otherwise, the action is identical with that described in conjunction with FIGS. 1 and 2.

The arrangement shown in FIG. 4 illustrates a pair of breaker arms 4 and 4' which are bridged by an actuator plate extending between the hub portions of the breaker arms 4 and 4' which are received on the pivot shafts 8 and 8'. In this case, the bellcrank 11 is provided with a finger portion lla engaging the plate 20 so as to shift the breaker arm in unison along their shafts 8 and 8' in the direction of the arrow of FIG. 4.

FIG. 5 shows somewhat diagrammatically a further embodiment of the invention which in this case, achieves not only the aforementioned relative wiping or rubbing action between the fixed and movable contacts, but also effects advance-retard characteristics as the breaker arm is axially shifted along its pivot shaft. In FIG. 5, the lobes 21a of the distributor cam 21' are helically extending as indicated and the rubbing block 22 of the associated breaker arm 4" is correspondingly angled as illustrated. The bellcrank associated with the breaker arm 4", which may be identical with the FIGS. 2 or 3 embodiments described, shifts the breaker arm 4" in the direction of the arrow F 1 so as to achieve not only the aforementioned wiping action but also to advance the make and break opening of the contacts with respect to the angular disposition of the rotor shaft to which the cam 21' is fixed.

The same effect may be achieved by inclining the pivot shaft 23 for the breaker arms 4" and 4"" as shown in FIG. 6 with respect to the axis of the rotor shaft, the distributor cam 24, in this case, having its cam lobes extending parallel to the axis of the shaft S in conventional fashion. By virtue of the inclination of the pivot shaft 23, the actuating mechanism in imparting motion to the breaker arms in the direction of the arrow F in FIG. 6 also cause the rubbing blocks 25 of the breaker arms to shift in the direction of the arrow F, relatively to the cam and thereby advance the make and break relationship between the fixed and closed contacts of the ignition distributor points.

Thus, by utilizing a manifold vacuum actuator for the bellcrank 11 in FIGS. 5 and 6, not only is the wiping action achieved, but also the automatic advance-retard motion is established.

What is claimed is:

I. In an ignition distributor having a rotor shaft, a cam driven by said shaft, and a breaker plate adjacent the level of said cam, in combination,

a fixed ignition point contact carried by said breaker plate, a breaker pivot shaft on said breaker plate, a breaker arm pivotally mounted on said pivot shaft having a contact remote therefrom for make and break engage ment with said fixed contact and having a rubbing block engageable by said cam, and means for shifting said breaker arm axially of said pivot shaft to cause relative movement between said fixed contact and said breaker arm contact for cleaning the contacts and for varying the ignition timing as a function of the vacuum as responsive to a function of the engine load. 2. In the ignition distributor as defined in claim I wherein said pivot shaft is parallel with said rotor shaft.

3. In the ignition distributor as defined in claim 1 wherein said pivot shaft is inclined with respect to the axis of said rotor shaft whereby said axial shifting of said breaker arm also effects change in the make and break timing of sa id contacts for cleaning t e contacts and for varying the ignition timing as a function of the vacuum as responsive to a function of the engine load.

4. In the ignition distributor as defined in claim 1 wherein said cam is provided with lobes extending helically of the axis of said rotor shaft whereby said axial shifting of the breaker arm also effects change in the make and break timing of said contacts.

5. An ignition distributor comprising a rotatable cam,

a fixed ignition contact and a breaker arm, said breaker arm being pivotally mounted remote from said fixed contact and having a contact engaging said fixed contact, said breaker arm also including a rubbing block engageable by said cam for pivoting said breaker arm in a predetermined plane away from said fixed contact, and

means for shifting said breaker arm back and forth perpendicular to said plane to effect relative wiping action between said contacts.

6. An ignition distributor as defined in claim 5 wherein said means includes a bellcrank engaging said breaker arm and a link for oscillating said bell crank.

7. In the ignition distributor as defined in claim 6 including a compression spring bearing against said breaker arm in opposition to said bellcrank.

8. The ignition distributor as defined in claim 5 wherein said breaker arm is shifted parallel to the axis of said cam, said cam having helical lobes whereby said shifting of the breaker arm also effects variation in the ignition advance characteristic of said contacts.

9. The ignition distributor as defined in claim 5 wherein said breaker arm is shifted along an axis inclined with respect to the axis of said cam, said cam having lobes parallel to its axis whereby said shifting of the breaker arm also effects variation in the ignition advance characteristic of said contacts. 

1. In an ignition distributor having a rotor shaft, a cam driven by said shaft, and a breaker plate adjacent the level of said cam, in combination, a fixed ignition point contact carried by said breaker plate, a breaker pivot shaft on said breaker plate, a breaker arm pivotally mounted on said pivot shaft having a contact remote therefrom for make and break engagement with said fixed contact and having a rubbing block engageable by said cam, and means for shifting said breaker arm axially of said pivot shaft to cause relative movement between said fixed contact and said breaker arm contact for cleaning the contacts and for varying the ignition timing as a function of the vacuum as responsive to a function of the engine load.
 2. In the ignition distributor as defined in claim 1 wherein said pivot shaft is parallel with said rotor shaft.
 3. In the ignition distributor as defined in claim 1 wherein said pivot shaft is inclined with respect to the axis of said rotor shaft whereby said axial shifting of said breaker arm also effects change in the make and break timing of said contacts for cleaning the contacts and for varying the ignition timing as a function of the vacuum as responsive to a function of the engine load.
 4. In the ignition distributor as defined in claim 1 wherein said cam is provided with lobes extending helically of the axis of said rotor shaft whereby said axial shifting of the breaker arm also effects change in the make and break timing of said contacts.
 5. An ignition distributor comprising a rotatable cam, a fixed ignition contact and a breaker arm, said breaker arm being pivotally mounted remote from said fixed contact and having a contact engaging said fixed contact, said breaker arm also including a rubbing block engageable by said cam for pivoting said breaker arm in a predetermined plane away from said fixed contact, and means for shifting said breaker arm back and forth perpendicular to said plane to effect relative wiping action between said contacts.
 6. An ignition distributor as defined in claim 5 wherein said means includes a bellcrank engaging said breaker arm and a link for oscillating said bell crank.
 7. In the ignition distributor as defined in claim 6 including a compression spring bearing against said breaker arm in opposition to said bellcrank.
 8. The ignition distributor as defined in claim 5 wherein said breaker arm is shifted parallel to the axis of said cam, said cam having helical lobes whereby said shifting of the breaker arm also effects variation in the ignition advance characteristic of said contacts.
 9. The ignition distributor as defined in claim 5 wherein said breaker arm is shifted along an axis inclined with respect to the axis of said cam, said cam having lobes parallel to its axis whereby said shifting of the breaker arm also effects variation in the ignition advance characteristic of said contacts. 